Investigation on Bacterial Growth and pH in Milk after the Expiration Date

Figure 2

Representative images of Petri dishes at different times after inoculation by milk samples opened at 1 and 9 days after expiration. Very few bacteria colonies were found in all three kinds of milk samples opened one day after expiration and cultured for 4 days (a). Although many bacteria colonies are found in all three milk samples opened 9 days after expiration and cultured for 4 days, very few bacteria colonies are found in the same milk samples opened 9 days after expiration and cultured for 24 hours (b). The bottom row shows an enlarged area with bacteria colonies.

(a)

(b)